66 MISC. PUBLICATION 43 4, U. S. DEPARTMENT OF AGRICULTURE 



~?"x/"x 4-6" ANGLE 

 5* I" STRAP IRON*} 



An important feature of nursery irrigation is leveling. In fields 

 which appear smooth and uniform to the eye, small irregularities of a 

 few inches may either divert the flow of irrigation water from the tree 



rows or cause pools to 

 form. To smooth out 

 high points and fill in 

 depressions, a drag or 

 irrigation leveler is 

 used (fig. 18), con- 

 sisting of a rectangular 

 frame from 16 to 24 

 feet long with cross 

 members spaced at 

 uniform intervals. 



Leveling may be 

 necessary for several 

 seasons to get the land 

 in the best shape for 

 irrigation, but consid- 

 erable benefit will re- 

 sult from one or more 

 levelings in the same 

 season. The leveler 

 should be used only 

 when the ground sur- 

 face is fairly dry and in 

 good tilth and the 

 soil will move readily 

 ahead of the cross 

 members. If possible, 

 the leveler should be drawn once lengthwise across the field, once cross- 

 wise, and once diagonally, each season after the soil has been plowed 

 or disked preparatory to planting. In sandy soils, where levelings 

 are likely to pulverize the topsoil and subject it to blowing, one level- 

 ing may have to suffice. Obvious high points and deep depressions 

 often require the use of a blade road-grader or slip scraper. 



'32 SHEET METAL 



Figure 17.- 



A common design of portable metal 

 dam. 



Figure 18. — Irrigation leveler used at Bessey Nursery, Halsey, Nebr. 



